Meter testing apparatus



Feb. 19, 1952 F. E. DAv|s,]]I

METER TESTING APPARATUS 2 SHEETSSHEET 1 Filed July 12, 1950 F. E.DAVIS,I|I METER TESTING APPARATUS Feb. 19, 1952 2 SHEETSSHEET 2 FiledJuly 12. 1950 Dal/58E [lave wfiar [Zeta jail; y W

jib C! 75 Patented Feb. 19, 1952 UNETED STATES PATENT OFFICE METERTESTING APPARATUS.

Flavius E. Davis, HI, Jackson, Mich.

Application July 12, 1950, Serial No. 173,423

6 Claims. 1

This invention relates to electrical control apparatus for comparing therate of rotation of a watt-hour meter with the rate of a rotatingstandard. In a comparison test the. meter to be tested and the rotatingstandard are connected under common or identical load conditions and arestarted simultaneously and rotated for the same length of time. Bothmeters are then stopped together and the number of rotations of themeter and standard are compared to determine the error, if any, in therate of rotation of the meter. In certain cases it is desirable to testthe meter under various current-load con ditions, and when three phasecurrent is used, with various power factors produced by a phasediiierence between the potential and current applied to the meter andstandard.

Control apparatus has been proposed for automatically energizing themeter and rotating standard, counting the revolutions of the meter anddeenergizing the standard after'a number of meter revolutions which maybe preselected according to the common load conditions. It has also beenproposed to employ more than one standard and prearrange the electricalcircuits including the loading devices and rotating standards so that asequence of tests may be performed more quickly and conveniently.Previous apparatus, however, has not been satisfactory in many instancesfor comparing a meter with a single rotating standard nor has itafforded an automatic comparison of the meter with a succession ofrotating standards.

One object of the present invention is to provide improved apparatus forstarting and stopping the rotating standard under the control of acounting device, and for insuring that both the counting device and therotating standard are in starting condition when the test is begun, andthat the counting device and standard are started together.

Another object is to provide control circuits for selecting one of aplurality of rotating standards for comparison with the meter. Thecircuits may be used to control individual comparison tests or anautomatic sequence of comparison tests in which a plurality of standardsare successively compared with the meter under different loadconditions.

In one aspect the invention involves a counting device such as astepping switch which responds to rotation of the meter under test so asto step from a rest position and count a preselected number ofrevolutions of the meter, relay means for starting the counting deviceand a automatic comparison of the meter with a rotating standardtogether, a holding switch closed by the counting device for apredetermined interval after said preselected number of revolutions haveoccurred, a stop relay energized by the counting device after saidnumber of revolutions for controlling the start relay means to stop therotating standard and, for holding the stop relay energized, a circuitincluding said holding switch, whereby after the preselected number ofrevolutions the stop relay is energized the start relay means arecontrolled to stop the standard, and after said interval the stop relayis deenergized. Preferably the apparatus includes a reset circuit forrestoring the counting means to rest position, said reset circuitincluding said holding switch and a switch of the stop relay so that thestop relay is held energized during said predetermined interval untilthe counting device is restored to rest position and is thereafterdeenergized. As will be set forth subsequently, other mechanism may beactuated by the stop relay during the interval in which it is heldenergized by the holding switch.

In a further aspect the invention comprises start relay means includinga standard-start relay for energizing the rotating standard, a teststartrelay for applying power to the standard and the counting means, and astart key for energizing the start relay, the start key including acontact for simultaneously applying power to reset mechanism associatedwith the rotating standard thereby restoring the standard to a startposition so that the standard will be in start pasi tion when acomparison test is commenced on release of the start key.

In another aspect the apparatus may be used to compare the meter withone of several standards under different load conditions and com prisesone or more control relays or like means for selectively interconnectingone of the rotating standards with the aforesaid standard-start relay, acontrol switch actuated to step through control positions, each of whichcorresponds to a standard so that the position of the control switchconditions the control relay means to select a standard, and presetswitches, each corresponding to a standard, for actuating the controlswitch to step to a position in which the desired standard is selected.

In a further aspect the invention cession of rotating standards, andcomp motor means for stepping the aforesaid switch from position toposition, the motor means being responsive to the aforesaid stop relay,so

that after the meter is compared with one standard and the countingmeans and holding switch energize and hold the stop relay, the saidstandard is stopped and other standard is selected and thereafter saidother standard and counting means are automatically controlled in asimilar manner.

In this aspect the apparatus preferably includes an auxiliary startrelay for by-passing the holding circuit of the test-start relay throughan auxiliary start circuit including a normally closed switch of thestop relay and a switch of the auxiliary start relay, so that thetest-start relay is deenergized each time the stop relay is energized,and energized when the stop relay is thereafter deenergized.

Preferably the auxiliary start relay is held energized through anauxiliary holding switch associated with the aforesaid control switchand, said auxiliary holding switch'being closed when the control switchis in a control position and open when the control switch is in otherpositions, so that the auxiliary start relay is held energized until thesequence of comparison tests with the several rotating standards iscompleted.

In a still further aspect the apparatus may be used for comparing themeter with an individual standard preselected by the aforesaid presetswitches, or with a sequence of successively selected standards, andcomprises a single-test start circuit including a start key forenergizing the test-start relay, an auxiliary start relay, a by-passswitch for breaking the single teststart circuit and connecting theauxiliary start relay with the start key, an auxiliary start circuit forthe test-start relay including a switch of the auxiliary relay and aswitch of the stop relay for energizing and holding the test-start relayenergized, whereby when the by-pass switch is in one position thetest-start relay is energized only by said start key to start a singlecomparison test, whereas if the by-pass switch is in its other positionthe start-relay is energized on each deenergization of the stop relay solong as the auxiliary start relay is energized to close the auxiliarystart circuit.

For the purpose of illustration typical embodiments of the invention areshown in the accompanying drawings in which Figs. 1 and 2 are schematicdiagrams of control apparatus.

Single-test apparatus Fig. 1 illustrates apparatus for controlling asingle comparison test between a watt-hour meter M and a rotatingstandard S. When prepared for a comparison test the current coil Im ofthe meter and the current coil Is of the rotating standard are connectedin series with a loading resistor L. The potential coil Em of the meteris connected across the power terminals A so that the meter is operatingwhenever current is applied at the power terminals. The circuit throughthe potential coil Es of the rotating standard S is interrupted by arelay switch do, so that although current is applied through the currentcoil Is the standard does not rotate until switch 4a is closed.

Associated with the meter M is a photoelectric device including aphotoelectric tube P and a lamp B. The lamp B is disposed so as todirect light through an anti-creep hole H in the rotating disk D of themeter M or toward the disk for interruption of the reflected light by asuitable mark or marks on the disk. On each partial or full rotation orcycle of the meter as the case may be or tl-tlfl to another.

the phototube P energizes a relay R5 which periodically closes keys 5aand 5b. Since the relay R5 produces keyed pulses of current in thecircuits connected to the keys 5a and 5b it may be described as a keyingrelay. Since the disk D is constantly rotating whenever power is appliedat the terminals A, the keying switches 5a and 5b will be opening andclosing prior to the time the rotating standard is started. Directcurrent power for the lamp B and the control circuits is furnished by arectifier R. If desired an alter nating current source direct may beused to 0perate the equipment arranged for such operation.

The control circuits for energizing the rotating standard anddeenergizing it after a predetermined number of revolutions of the metercomprises a manual start key l3a, a test-start relay R2 which may beenergized by transferring the start switch I3a, a standard-start relayR4 for closing the potential circuit of the rotating standard, a stoprelay R3 and a counting device including a stepping relay Rl and theassociated holding switch la and counting switch lb. The holding switchla is a bridging wiper which holds a circuit through one contact untilit has been stepped to an adjacent contact, but may also be a contactthat is closed in all positions of switch lb except the rest position 1when it is open.

The standard-start relay R4 is energized through a circuit including thestart switch l3a, the keying switch 5a, the counting switch lb, thestart contact s of the counting switch and a switch 20 of the test-startrelay R2. Holding circuits are provided for the test-start relay R2 andthe standard-start relay R4. The holding circuit for the test-startrelay includes a switch 312 of the stop relay R3 and a switch 2a of theteststart relay. The holding circuit for the standardstart relayincludes a switch 3b of the stop relay and a switch 4b of thestandard-start relay.

The stepping relay RI actuates a ratchet device Gl each time it isdeenergized. The ratchet device Gl on each actuation steps the switchesor wipers la and lb from one of the contacts 1', s As the countingswitch lb steps from rest position 1' it completes a circuit, firstthrough a start contact s and then through stop contacts tl-tl 0. Whenthe counting switch lb is in the start position s a pulse of current istransmitted by the keying relay through a switch 20 of the start relayR2 to the standard-start relay R4. At each of the stop contacts tltll]are preset switches I2. Although shown as ordinary switches preferablyswitches l2 are interlocked so that only one remains closed at a time.When the counting switch lb reaches one of the contacts tl-tl 0 which isconnected to a closed preset switch a pulse of current is transmitted bythe keying switch 5a to the stop relay R3.

The stop relay after energization when the counting switch reaches astop contact is held through a circuit including a switch 3b of the stoprelay, the holding switch Ia and another switch 3a of the stop relay.

The stepping relay RI may be actuated either through a main motorcircuit or an auxiliary motor circuit. The main motor circuit includesthe start switch l3a, a switch 5b of the keying relay and a switch 2b ofthe test-start relay R2. The main motor circuit is closed periodicallyby the keying relay R5 which applies pulsed current to the steppingrelay RI. When each pulse the stepping relay BI is energized and thendeenergized. On deenergization it steps the holding switch la and thecounting switch lb. The

auxiliary motor circuit includes a switch 31) of the stop relay, theholding switch la and an inertia switch lc. When the auxiliary circuitis closed the stepping relay RI operates the inertia switch to so thatit opens and closes, periodically actuating the stepping relay RI. Theinertia switch is weighted so that it cannot complete a.

number of revolutions which will afford an accurate comparison willdepend on the speed of the meter and the standard, which in turn willdepend upon the load placed upon the meter and the standard. If the loadis light one to four revolutions may be suflicient; if the load is heavyfive to ten revolutions may be required for an accurate comparison.

Single test operation When a preset switch has been closed the test isstarted by transferring contact Eta of the start switch to apply currentfrom the positive terminal to the start relay R2. R2 will then beenergized closing the switches 2a to 20, and will be held energizedthrough the switch 2a. When the start switch lSa is transferred thereset switch l3b will apply power to the reset relay R9. The startswitch is not released until the standard is in starting position.

After the start switch [3a is released and on the next closing of thekeying relay R5 the main motor circuit is closed and stepping relay RIis energized and deenergized stepping the counting switch lb and theholding switch Ia to the start contact 5. such condition that on thenext subsequent closing of the keying relay the standard-start relay R4is energized and then held through its holding circuit. At the same timethe stepping relay is energized through the main motor circuit steppingthe counting switch lb to contact tl. Thus, the meter and the standard Sbegin a cycle as the counting switch begins to count the revolutions ofthe meter.

As the meter and standard rotate through a succession of comparisoncycles the counting switch and holding switch are stepped from contactto contact at the same rate as the rate of revolution of the meter. Whenthe counting switch reaches one of the contacts tl-tin which isconnected with a closed preset switch E2 the stop circuit is completedenergizing the stop relay R3. The stop relay is held through its holdingcircuit including switches 3b, la and 3a. When switch 32: is transferredthe holding circuits of the test-start relay and the standardstart relayare broken deenergizing these relays. When the start relay opens themain motor circuit is opened and when the standard-start relay opens thecircuit to the potential coil of the rotating standard is openedstopping the standard.

When the contact 31) of the stop relay R3 is transferred the auxiliarymotor circuit is com pleted through switch 312, the holding switch laThe standard-start circuit is then in and the inertia switch Id. Thestepping relay is then intermittently actuated through its inertiaswitch stepping the holding switch to the rest contact r. Since theholding switch la is a bridging wiper it does not break the holdingcircuit of the stop relay as it steps to any of the contacts ii to H0.When the holding switch lb is stepped to the rest contact 1* the stoprelay holding circuit is broken deenergizing the stop relay and openingthe auxiliary motor switch. The counting switch is then in position tobegin another test.

If at any time during the test it is desired to stop the test the key [4is closed energizing the stop relay R3 and initiating the reset cycledescribed in the preceding paragraph.

Semi-automatic apparatus The embodiment of the invention illustrated inFig. 2 includes all the elements of the embodiment of Fig. l with theaddition of control circuits for comparing the meter with any one ofthree rotating standards SI to S3. The first rotating standard SI isconnected for a heavy or full-load comparison test, the third standardS3 for a light-load test, and the second standard S2 for a 50% powerfactor test in which the potential is out of phase with the currentmeasured. The current coils Is of the first and second rotatingstandards Si and S2 are connected in series with a heavy-load resistanceFL while the current coil of the third standard S3 is in series with alight-load resistance LL.

The control circuits include a stepping relay and the associatedstepping switches Illa-lilo, control relays R6 and R1, and an auxiliarystart relay R8. The potential coils Es may be selectively connected withthe standard-start relay R4 by the control relays R6 and R1 in such away that only one of the potential coils Es will be energized at a time.A switch la of the control relay Rl determines whether potential betweenthe power terminals X and Z which is in phase with the current, orpotential between the power terminals X and Y which is out of phase withthe current, is applied to the full-load and light-load standards or tothe 50% power factor standard respectively. Power terminals X, Y and Zare arranged for connection with a three phase power supply. If singlephase current is used the power lines are connected with terminals X andZ and a phase changing capacitance C or equivalent phase-shiftingnetwork is interposed between the power terminal Z and the switch la bytransferring the contacts of switch 23.

Connected to certain of the stop contacts tI-tlfl of the counting switchlb are three sets of preset switches, a light-load set l2a, a 50% powerfactor set 121) and a full-load set I20, each corresponding to one ofthe three rotating standards, and effective only when the correspondingstandard is connected with the meter under test.

The stepping relay Rlfl is associated with a meter selecting or controlswitch Illa, an auxiliary holding switch I lib and a stepping switchlilo. The meter selecting or control switch Illa has sets of controlcontacts cl to c3 and neutral contacts n. Contacts 02 and 03respectively are connected to the control relays R6 and R1. When thecontrol switch lea is in either of these positions a control circuit iscompleted through the switch 31) of the stop relay R3, the switch orwiper la, the contacts c2 or c3 and thence to the two'control relays R6or R1. In control position cl and the neutral positions n the control 7switch Illa does not affect the controls R6 and R1 and they will be intheir normal deenergized condition, that shown in Fig. 2.

Relay R determines which of the three standards, the light-load standardS3, the full-load standard SI or the 50% power factor standard S2, is tobe compared with the meter M. In the condition shown, switch So of thecontrol relay R5 connects the current coils Is of the full-load standardSI and the 50% power factor standard S2, which are in series with thefull-load resistor FL and the current coil Im of the meter M. In theposition not shown switch 60 connects the current coil Is of thelight-load standard S3 in series with the light load resistor LL and thecurrent coil Im of the meter M. Switch Eb of the control relay R6 in theposition shown connects the potential coil E5 of the full-load standardSI to a switch 4a of the standard-start relay R4 through a switch 1c ofthe control relay R'I. In its other position switch rib connects thepotential coil Es of the light-load standard S3 directly with thestandard-start relay switch la. Switch 6a of the control relay RE, asshown, connects a full-load set of preset switches I through switch 11)to the stop relay R3 so that this set of switches only will be effectiveto stop a test comparing the meter M and the full-load standard SI. Inits other position the switch Ea connects the lightload set of presetswitches IZa with the stop relay. lhus, the control relay R6 selectivelyinterconnects both the current coils and the potential coils of thefull-load or light-load rotating standards in series with the meter andthe proper load, and selects the proper preset switches.

Control relay R1 is energized when the co-ntrol switch Illa is in aposition at the control contact 03. In this position the control R6 isdeenergized and is in the condition shown in Fig. 2

with its switch 60 connecting both the full-load will be connected withthe standard-start relay switch ta through the control relay switch 6b.Switch lb of the control relay R! connects either the full-load set ofpreset switch I20, as shown in Fig. 2, or the power factor set I2b.Switch 'I a selects either the potential at the power terminal Z whichis in phase with the current at the power terminal X or out-of-phasepotential at terminal Y or the capacitor C.

A set of auxiliary preset switch Ila to He are used to predetermine theeffect of the stepping relay RI 1 and its stepping switches IIlaI lid.The ganged set of switches I la and I II) are transferred when it isdesired to compare the meter successively with each of the threestandards SI- SS as will be hereinafter explained. The remaining presetswitches I IcI le are used to preselect any one of the three standardsfor comparison with the meter. The auxiliary preset switches may beordinary switches as shown but preferably are interlocked so that onlyone I Ic-I Ie or the ganged switches I Ia and I I1) may be transferredat one time. Each of the preset switches No to He corresponds to one ofthe rotating standards SI to S3. When one of the preset switches I I0 toI Is is transferred, the stepping switch IIlc completes a preset circuitto the stepping relay RI 0 unless the stepping switch I90 is in aposition corresponding to the selected meter. For example, if switch IIcwere transferred and if the stepping switch I00 were in position atconof the switches trol contact 02 a preset circuit would be completedthrough the switch 3b of the stop relay R3, the switch IIic contact 02,preset switch IId, preset switch Ho and the inertia switch I911 of thestepping relay RIO. RIO would be energized opening the inertia switchloci, and then deenergized stepping switches Illa-I00 to position 03.The preset circuit would still be completed through contact 03, switchHe, and switch lie so that the control relay RIO would step the switchesto one of the neutral contacts 11. At these contacts the preset switchesare bypassed and the preset circuit is again completed, so that theswitches would be stepped to contact'cl corresponding to the presetswitch Me which has been transferred. As previously explained in thisposition the control relay R6 and R1 select the full-load standard SIwhich was preselected by transferring preset switch I I0.

Fully automatic apparatus Fully automatic apparatus for successivelycomparing the meter M with all of the rotating standards SI to S3,involves an auxiliary start relay R8, the ganged Icy-pass switches Ilaand III), and an auxiliary holding switch Hit). The by-pass switch Ilaconnects the auxiliar start relay R8 with the start switch I3a. Theauxiliary start relay is held energized through a holding circuitincluding the stop switch I4, the auxiliary holding switch I Jb, theholding contact cI-c3 and a switch 8a of the auxiliary start relay. Aswitch 81': of the auxiliary start relay completes an auxiliary startcircuit including switch 32) of the stop relay, and the switch 82). Theswitch connects the stepping relay RI 0 directly with the switch 31) ofthe stop relay to provide a holding circuit for relay RIB whichIcy-passes the control contacts cI-c3 of the stepping switch I60 and theinertia switch Hid. Since the stepping relay RH) actuates the ratchetmechanism G2 only on deenergization, the relay RIO can be actuated ifthis holding circuit is opened only when the step relay is energized andthe switch 31) transferred of when switch 80 is opened. When switch 80is opened, by-pass switch IIb provides a reset circuit through switch311 of the stop relay, stepping switch I00, and thence through thecontacts 02 or 03, the switches IId or Me and switch I Ic and I Ib orthrough a neutral contact n and the inertia switch IIId to the relayRIO. Thus, if switch 32) of the stop relay is in the position shown andthe by-pass switch I I1) is transferred the stepping switch Iflc will bestepped to contact cI unless it is already in that position.

Semi-automatic operation For semi-automatic operation using theapparatus of Fig. 2 for a single comparison test between one of thestandards and the meter, one of the preset switches I I c-I Ie istransferred causing the control device to step to a position in whichthe control switch Illa selects the desired standard. One switch of thecorresponding set of preset switches IZa, 12b or I 20 is closed and thestart switch I3a-I3b is then transferred energizing the test-start relaythrough switch Ila. As described with reference to Fig. 1 the countingswitch It is stepped to the start position s on the next closing ofkeying relay R5, and on the following closing of keying relay thestandard-start relay R4 is energized connecting the desired standard inseries with the meter and the proper load. With each closing of thekeying relay the counting switch is stopped until it reaches a contactwhich is connected to the closed preset switch 9 in the setcorresponding to the selected standard. The "stop "relay is thenenergized, deenerg-izing *the start-relays-and-stopping the standard.

Fully. automatic. operation For fully r automatic operation :.the gangedbypass' switches Ha"l lb are transferred=from the position -shown in.Fig. 2 causing .athe stepping switches Illai 60 to step to :the full.'-.load position at the "control contact :cl. Oneswitch'of each set ofthe counting preset switches :2al2c is then closed. When the startswitch:l:3a:l'3b is transferre'd the auxiliaryi-start relayis-"energized through switch i I la, "and it in "turn s-energizes thetest start relay R2ithr0ugh switch r8b. When start switch l3a-l3b.isreturned andithe keying ::sw-itch 512 :next closes, the counting switch1 lb i is steppedflto ithe=fstarirposition :s, and on-the next closing'ofzthe :keyi-ng' switch Sa'the standard-start relay .R i :is energizedthrough the countingswitch 1b and'th'e switch 20 of'tthe.

test-start relayiRZ. Subsequentclosingsof the keying switch 51) advance'the counting switch lb'to one of thesstop contacts tl'-.tl0 connectedwith the set of preset. switches HQ The control'relays-Rfiand R7 are in'the condition shown in Fig. 2 in which the set lZc of'presetswitches isconnected with the stop :relay-through relay switchesfia and lb. Thestop relay-is energized and then held throughholding switch la thusdeenergizing the start relays R2 and R4 and breaking the circuit throughswitch "80' to the stepping relay R 0' thus causing stepping switch:lilcand-theassociate'd switches: 16a and Y I 0b to step-to contact c2.Switch 31) of theSt0pLTBIBIY'TZJSOBIOSES'the :auxiliary motor circuit:through "the holding switch Ia and the inertia'switchfic-tothe'stepping :relay R! causing the :"stepping switch to advanceto therest positionm -=The=stop-relay is "then deenergized and. switch 31)senergizes the test-start relay and the1stepping relay RH].

Since the control switch has been stepped to contact a2 thecontrolrelays R6 and :R! ihav-e connected the current coil of the 50%*poweriactor standard S2 in series with full-load resistance SL andthemeteriM, and connectedthe potential coilEs of the standard:S2with-the'standard-startrelayR and with the out-'of-phase :terminal Y.'On the'first closing of the keying switch '52) thecounting switch lbisnagain stepped torits start position-s. On thenext-subsequent closingthe standard-startrelay R4 is actuated 'energizing'the potential coil ofthe second stand ard I S2. A comparison test between the second standardand the meter thenrproceedsuntil'the counting switch 'reaches a contact.connected to.

one of 'the closed preset switches rof the 50% power: factor. set. 82b.:The stop relay: is then. energized; the control switch l IGaradVa-ncedto contact c3 and'the countingsw-itch restored tor-rest :position 7'ashefore. The meter-is :thenready ffOl' comparison with'thethirdstandard slrand aithird comparison test is run.

-At the end ofthethirdtest the stop relay is energized through closed.:switch of the light load preset switches-i211 resetting the;countingzswitch .to rest position. and "causingthe "holding switch it?)and the stepping switch I 00 to-advance to a neutral contact -n. 'Whenthe auxiliary holding switch Hib isin the neutralrpos-itien-thesauxiliary start relay is deenergized and switchtb opens theauxiliarystart circuit for the -teststart relay so that-the -test startrelay cannot .be energized again when the stop .relay. is-deenergized..While the stepping switch l0c. is in 10 neutral position the resetcircuit for the stepping *relay R1 0 --will,-=-whenthe stoprelay issubsequently deenergized, be completed through switch '31),stepping-switch 100, the neutral con- 5 tact n andthe inertia switchlfid to the stepping relay Rl ll, andthe stepping relay will advance the--stepping switch to the next contact cl. Since *the "switch 'I I b hasbroken the circuit "through-contact cl 'to'the inertia switch liib thesteppin'gswitch'will stop in" this position in readinessfor'thenext'sequence of comparison tests. If i it 'is desired tointerrupt "the sequence of 'tests, the stop-reset switch 14 istransferred breaking the holding circuit of the auxiliary start relay RBandenergizing the'stop relay R3. When "switch 3b -transfers'the steppingrelay R!!! will be deenergize'd advancing the'stepping switch oneposition. "The holding'an'd counting switches la -and* lb -willbe resetto rest' position whereupon zu' the 'stop relay will be 'fdeenergized.When switch 3b of thestop relay returns to the position shown =in'Figf2therreset-circuitfor the stepping relay Rf-U is 'completed"th1ough thepreset switches lb-Hc 'or through theneutral contacts nto is the inertiaswitch led restoring the stepping switchlflcand-the associated switcheslea and" I 85 to a position at control contact cl.

"Thus' with the apparatus of Fig. 1 a sin'le "meter may' be testedand'the control apparatus as :"automatically restored to startingcondition. Theapparatus of Fig. 2 adapts the circuits of Fig.lforsemi-automatic orfully automatic comparison with a plurality ofmeters.

It shm'Jldbe understoo'd'that thepresent dis- *closure'isfor the purposeof illustration only and that this invention' includes all modificationsand equivalents which fall within the scope of the ap- E pended claims.

l'claimz =1. 'For'comparing'the rate of-revolution'of a I current meterwith that of "a rotating standard i underlikeload conditions; testapparat s compris I sing start relay means including astandard-sta rt:relay% for applying power to the rotating standard andz-a test-startrelay for actuating the standardstartvrelay, astoprelay for controllingthe test- -start relay a holding circuit for the stop relay, mounting"means responsive to the meter to step "from astart position through aseries of stop positions-ata'rate proportional to the rate of revolutionofmthe metergsaid' counting means including a -.-counting-swi-tchforactuating the stop relay a preselected number of revolutions of themeter after power is applied to the rotatingstandard nand a holdingswitch in the holding circuit of the stop relay closed-when thecountingit- .is. in a stop positionya main circuit for applying \power tosaidcounting means including a switch ..of..thetest-startrelay, and forrestoring said 50 counting means to rest. position an auxiliary circuitincluding a switch of the stop. relay, whereby aftera selected. numberof revolutions the stand- .ard isstoppedand themain circuit is openedibut .the counting meanscontinuesto operate through said auxiliarycircuit until said counting .means reachesa rest position.

'2. For comparing the rate. of revolution of a wattrhour. meter withthatof a rotating standard under likeloadconditions, testing apparatus..compri'sing..a, counting switch movable through ..av series of,positions including. in sequence a rest ,position,..a. start position,.and a seriesof stop ,positionsand thenceto arest position, a startcontact .1.at-;the..start position, stop contacts at .the stoppositions, a holding switch associated with the counting switch, thecontacts of the holding switch being closed when the counting switch isin stop positions and open when the countin switch is in anotherposition, a motor for stepping said switches from contact to contact, amain motor circuit for connecting the motor to a power source, keyingmeans responsive to the meter for modifying said main motor circuit toactuate the motor at a rate proportional to that of the meter, atest-start relay for closing the main motor circuit, a standardstartrelay for starting the rotating standard, a circuit for thestandard-start relay including a switch of the test-start relay, a startcontact of said counting switch and a switch of the keying relay,whereby the rotating standard starts when the keying relay functionswhile the counting switch is in start position, a holding circuit foreach of said starting relays, a stop relay for breaking said holdingcircuits, revolution preset switches for connecting the stopping relaywith any one of the stop contacts of the counting switch, a holdingcircuit for the stop relay including said holding switch, and anauxiliary motor circuit including said holding switch whereby, when thecounting switch reaches a stop contact connected to a closed presetswitch, the rotating standard is stopped and the main motor circuit isopened but the motor continues to operate through said auxiliary motorcircuit until the counting and holding switches reach a rest position.

3. For comparing the rate of revolution of a meter with the rate of eachof a plurality of successively selected rotating standards, apparatuscomprising means responsive to said meter for counting the revolutionsof the meter, start relay means energizedto apply power to said countingmeans and to a selected standard, a stop relay actuated by the countingmeans after a predetermined number of meter revolutions to deenergizesaid start relay means, control relay means having a plurality ofconditions in each of which a different rotatin standard is connectedwith the start relay means, for actuating the control relay means acontrol switch having a control position for each standard, the positionof the control switch determining the condition of the control relaymeans, motor means responsive to the stop relay to step the controlswitch from position to position, an auxiliary start relay, a start keyfor energizing said auxiliary start relay, a start circuit for applyingpower to the start relay means including a switch of the auxiliary startrelay and a switch of the stop relay, and a step circuit for the motormeans including said start circuit switches, whereby when said stoprelay is energized by the counting means said start circuit is openeddeenergizing said start relay means to stop one standard, and alsodeenergizing said motor means to step the control switch to a positionin which another standard is selected, and when the stop relay isdeenergized after said predetermined interval the start relay means isenergized to start said other standard.

4. For comparing the rate of revolution of a meter with the rate of eachof a plurality of successively selected rotating standards, apparatuscomprising means responsive to said meter for countin the revolutions ofthe meter, start relay means energized to apply power to said countingmeans and to a selected standard, a stop relay actuated by the countingmeans after a predetermined number of meter revolutiog Q9 deenergizesaid start relay means, control relay means having a plurality ofconditions in each of which a difierent rotating standard is connectedwith the start relay means, for actuating the control relay means acontrol switch having a series of control positions, one for eachstandard, and neutral positions, the position of the control switchdetermining the condition of the control relay means, motor meansresponsive to the stop relay to step the control switch from position toposition, an auxiliary holding switch closed when the control switch isin a control position and open in other positions, an auxiliary startrelay, a start key for energizing said auxiliary start relay, a startcircuit for applying power to the start relay means including a switchof the auxiliary start relay and a switch of the stop relay, a holdingcircuit for the auxiliary start relay including said auxiliary holdingswitch, a step circuit for the motor means including said start circuitswitches, whereby after each standard in succession has been comparedand said control switch is stepped to a neutral position, the auxiliaryholding switch is opened breakin said start circuit and rendering thestop relay ineffective to start another test.

5. For comparing the rate of revolution of a watt-hour meter with thatof a first rotating standard under one load condition and subsequentlycomparing said rate with that of another standard under different loadcondition, test apparatus comprising a standard-start relay for applyingpower to the rotating standard, a teststart relay for controlling thestandard-start relay, a stop relay for deenergizing the test-startrelay, a holding circuit for the stop relay, counting means responsiveto the meter to step from a rest position through a series of stoppositions at a rate proportional to the rate of revolution of the meter,said counting means including a counting switch for actuating the stoprelay a preselected number of revolutions of the meter after power isapplied to the rotating standard and a holding switch in the holdingcircuit of the stop relay closed in said stop positions, a main circuitfor applying power to said counting means including a switch of thetest-start relay, and an auxiliary circuit including a switch of thestop relay for restoring said counting means to rest position anddeenergizing the stop relay, whereby after a selected number ofrevolutions the standard is stopped and the main circuit is opened butthe counting means continues to operate through said auxiliary circuituntil said counting means reaches a rest position and said holdingswitch opens the holding circuit of the stop relay; and for subsequentlycomparing the meter with another rotating standard under different loadconditions, a control switch responsive to the aforesaid stop relay tostep through a series of positions including a control position for eachstandard, control relay means having conditions determined by therespective control positions of said'selecto-r switch for successivelyinterconnecting each of the rotating standards with the aforesaidstandard-start relay, a manual start key, an auxiliary start relayenergized by said start key, and an automatic start circuit including aswitch of the auxiliary start relay and a switch of the stop relay,whereby after the first standard is stopped and said counting means isrestored to rest position, said stop relay energizes the teststart relaythrough said automatic start circuit and the meter is compared with saidsecond standard-start relay,

6. For comparing the rate of revolution of a watt-hour meter with thatof a first rotating standard under one load condition and, subsequentlycomparing said rate with that of another standard under different loadcondition, test apparatus comprising a standard-start relay for applyingpower to the rotating standard, a teststart relay for controlling thestandard-start relay. a stop relay for deenergizing the test-startrelay, a holding circuit for the stop relay, counting means responsiveto the meter to step from a rest position through a series of stoppositions at a rate proportional to the rate of revolution of the meter,said counting means including a counting switch for actuating the stoprelay a preselected number of revolutions of th meter after power isapplied to the rotating standard and a holding switch in the holdingcircuit of the stop relay closed in said stop positions, a main circuitfor applying power to said counting means including a switch of thetest-start relay, and an auxiliary circuit including a switch of thestop relay for restoring said counting means to rest position anddeenergizing the stop relay, whereby after a selected number ofrevolutions the stande ard is stopped and the main circuit is opened butthe counting means continues to operate through said auxiliary circuituntil said counting means reaches a rest position and said holdingswitch opens the holding circuit of the stop relay; and for subsequentlycomparing the meter with another rotating standard under different anMa;

stopped and said counting means is restored to,

rest position, said stop rel-ay energizes the test start relay throughsaid automatic start circuit and the meter is compared with said secondstandard-start relay, and a preset switch for selectively connectingsaid start switch to the aforesaid test-start relay or to said auxiliarystart relay, whereby the test apparatus may be used for a single test orfor a sequence of tests under different load condition.

FLAVIUS E. DAVIS, III.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS I Date Number Name 2,013,393 Strattner Sept. 3,1935 2,249,068 Wagner July 15, 1941 2,435,522 Wagenknecht Feb. 3, 1948

